The present device relates to a luminous pointer made of a light emission element which is of the organic substance dispersion type which can be accurately read and which is low in cost.
A light emission element of the inorganic substance dispersion type has been widely used for the measuring instrument of a motor vehicle, a show window or the like.
A conventional flat such element has the basic construction as shown in FIG. 7. The element includes a metal plate base 1, an electrically-insulating reflective layer 2 made of a vitreous enamel and disposed on the base, a fluorescent light emission layer 3 disposed on the reflective layer, a transparent electroconductive film 4 disposed on the light emission layer, and a transparent protective layer 5 disposed on the film. The reflective layer 2 is made of the vitreous enamel which is high in dielectric constant to increase an electrical field to be applied to the light emission layer 3 and is white in color for reflective purposes. The light emission layer 3 is made of an enamel and, a fluorescent substance dispersed therein. The film 4 is an ITO film indium-tin oxide or, more specifically, tin doped indium oxide or the like, and is formed on the light emission layer 3 by evaporative deposition, sputtering or the like. The transparent protective layer 5 constitutes the surface of the element, electrically insulates it from the outside, and protects the element. The element also includes an electrode 1a disposed on the metal plate base 1, and an electrode 4a disposed on the film 4. When a voltage is applied from a power supply 7 to the electrodes 1a and 4a through wires 6, the electric field is generated in the light emission layer 3 so that the fluorescent substance emits light. The flat element has been widely used for the dial of the measuring instrument of a motor vehicle or the like.
An art of manufacturing a luminous pointer which itself emits light and has the same light emitting function as the conventional light emission element is conceivable, but people have been hesitant to put the art into practical use, because of problems described from now on., Although the diameter of the pointer needs to be very small to enable accurate reading, it is difficult from viewpoints of material and processing to manufacture a light emission element which is of the inorganic substance dispersion type and is shaped as a pointer of 1.0 mm or less in diameter. This is one of the problems. Since the element includes an expensive ITO film as a transparent electroconductive film, the element is high in cost. This is another problem.